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Some success with a age old GRiD problem

Dagwood

Experienced Member
Joined
Oct 16, 2018
Messages
55
Good job, it isn't easy! I modded my 1520 for a CF card awhile back and it took me several days to nuke the fingerprinting and brute force the HDD type and desired geometry. I'm now revisiting it to spiff it up a bit (autodetect geometry, no drive, etc.).

I'm curious if your 1530 used the same technique as my old 3/11/89 1520 BIOS? Basically it queries the drives ATA ID to memory, parses it for the Conner CPXXX model number string, compares that against a predefined data table of compatible hard drive model numbers, then sets the CMOS HDD Type accordingly. Is yours the same?

Once again... great job
 

Klyball

Experienced Member
Joined
Feb 15, 2014
Messages
94
Location
Surrey, BC
As far as i can tell they use the same code more or less for all the 15xx models except i have one 1530 that has a stripped down bios with a jumper on the HD interface board 40 or 100mb that one is easy, just change the drive table.
all the rest you can either just set the drive table pointer and jump over the drive check or add in your drive along with the chs and keep the conner drive access also.
there is a bunch of ways to patch it when you find where to look. The easiest way would be set dx to the table right at the beginning and just jmp over

don't forget to add in your chs and fix the check sum

here are 2 examples of the code in question

1520

Code:
0000769e  53                 push    bx {var_4_1}
0000769f  51                 push    cx {var_6_1}
000076a0  1e                 push    ds {var_8_1}
000076a1  56                 push    si {var_a_1}
000076a2  06                 push    es {var_c_1}
000076a3  57                 push    di {var_e_1}
000076a4  ba0000             mov     dx, 0x0  
000076a7  e8f7a7             call    sub_1ea1			{Call to retrive drive 40 character drive id string}
000076aa  7306               jae     0x76b2

000076ac  ba55aa             mov     dx, 0xaa55
000076af  eb7b               jmp     0x772c

000076b2  b92800             mov     cx, 0x28  			{set counter for the id string}

000076b5  26803d2d           cmp     byte [es:di], 0x2d  	{find the "-" in the string}	 
000076b9  7407               je      0x76c2

000076bb  47                 inc     di
000076bc  e2f7               loop    0x76b5

000076be  f8                 clc     
000076bf  eb68               jmp     0x7729

000076c2  47                 inc     di

000076c3  26803d20           cmp     byte [es:di], 0x20		{move past the " " to the first character of id}
000076c7  7505               jne     0x76ce

000076c9  47                 inc     di
000076ca  e2f7               loop    0x76c3

000076cc  eb5e               jmp     0x772c

000076ce  8bdf               mov     bx, di
000076d0  ba0500             mov     dx, 0x5  
000076d3  8cc8               mov     ax, cs
000076d5  8ed8               mov     ds, ax
000076d7  be3cf6             mov     si, 0xf63c				{address of dive string}
000076da  b90600             mov     cx, 0x6  {"CP3022"}		{lenght of string}
000076dd  f3a6               rep cmpsb byte [si], [di]  {0xf63c}	{check string}
000076df  744b               je      0x772c				{jump if good or continue}

000076e1  ba0500             mov     dx, 0x5  
000076e4  8bfb               mov     di, bx
000076e6  be42f6             mov     si, 0xf642
000076e9  b90600             mov     cx, 0x6  {"CP3024"}
000076ec  f3a6               rep cmpsb byte [si], [di]  {0xf642}
000076ee  743c               je      0x772c

000076f0  8bfb               mov     di, bx
000076f2  ba0600             mov     dx, 0x6  
000076f5  be54f6             mov     si, 0xf654
000076f8  b90500             mov     cx, 0x5  {"CP344"}
000076fb  f3a6               rep cmpsb byte [si], [di]  {0xf654}
000076fd  742d               je      0x772c

000076ff  ba0900             mov     dx, 0x9  
00007702  8bfb               mov     di, bx
00007704  be48f6             mov     si, 0xf648
00007707  b90600             mov     cx, 0x6  {"CP3044"}
0000770a  f3a6               rep cmpsb byte [si], [di]  {0xf648}
0000770c  741e               je      0x772c

0000770e  8bfb               mov     di, bx
00007710  be4ef6             mov     si, 0xf64e
00007713  b90600             mov     cx, 0x6  {"CP3042"}
00007716  f3a6               rep cmpsb byte [si], [di]  {0xf64e}
00007718  7412               je      0x772c

0000771a  8bfb               mov     di, bx
0000771c  ba0700             mov     dx, 0x7  
0000771f  be59f6             mov     si, 0xf659
00007722  b90600             mov     cx, 0x6  {"CP3104"}
00007725  f3a6               rep cmpsb byte [si], [di]  {0xf659}
00007727  7403               je      0x772c

00007729  ba0000             mov     dx, 0x0 				{fail} 

0000772c  1e                 push    ds {var_10_1}
0000772d  50                 push    ax {var_12_1}
0000772e  b84000             mov     ax, 0x40
00007731  56                 push    si {var_14_1}
00007732  bec300             mov     si, 0xc3
00007735  8bc2               mov     ax, dx
00007737  ab                 stosw   word [di]
00007738  5e                 pop     si {var_14_1}
00007739  58                 pop     ax {var_12_1}
0000773a  1f                 pop     ds {var_10_1}
0000773b  5f                 pop     di {var_e_1}
0000773c  07                 pop     es {var_c_1}
0000773d  5e                 pop     si {var_a_1}
0000773e  1f                 pop     ds {var_8_1}
0000773f  59                 pop     cx {var_6_1}
00007740  5b                 pop     bx {var_4_1}
00007741  e956ff             jmp     0x769a

sub_7744:
00007744  1e                 push    ds
00007745  2e8e1ed9c6         mov     ds, word [cs:0xffffffffffffc6d9]
0000774a  8a16b200           mov     dl, byte [0xb2]
0000774e  32e4               xor     ah, ah
00007750  1f                 pop     ds
00007751  c3                 retn

1550sx

Code:
00013c80  53                 push    bx 
00013c81  52                 push    dx 
00013c82  1e                 push    ds 
00013c83  56                 push    si 
00013c84  06                 push    es 
00013c85  57                 push    di 
00013c86  ba0000             mov     dx, 0x0
00013c89  e8836a             call    sub_1a70f  {Get Drive Info}
00013c8c  724e               jb      0x13cdc

00013c8e  b92800             mov     cx, 0x28  

00013c91  26803d2d           cmp     byte [es:di], 0x2d  {Find the "-"}
00013c95  7405               je      0x13c9c

00013c97  47                 inc     di
00013c98  e2f7               loop    0x13c91

00013c9a  eb40               jmp     0x13cdc

00013c9c  47                 inc     di

00013c9d  26803d20           cmp     byte [es:di], 0x20 {look for " " then move to first character}
00013ca1  7505               jne     0x13ca8

00013ca3  47                 inc     di
00013ca4  e2f7               loop    0x13c9d

00013ca6  eb34               jmp     0x13cdc

00013ca8  8bdf               mov     bx, di
00013caa  8cc8               mov     ax, cs
00013cac  8ed8               mov     ds, ax
00013cae  ba0900             mov     dx, 0x9
00013cb1  bea73b             mov     si, data_3ba7
00013cb4  b90600             mov     cx, 0x6
00013cb7  f3a6               rep cmpsb byte [si], [di]  {cp3044}
00013cb9  7421               je      0x13cdc

00013cbb  8bfb               mov     di, bx
00013cbd  ba0c00             mov     dx, 0xc
00013cc0  bead3b             mov     si, data_3bad
00013cc3  b90700             mov     cx, 0x7            
00013cc6  f3a6               rep cmpsb byte [si], [di]  {cp30104}
00013cc8  7412               je      0x13cdc

00013cca  8bfb               mov     di, bx
00013ccc  ba1100             mov     dx, 0x11
00013ccf  beb43b             mov     si, data_3bb4
00013cd2  b90700             mov     cx, 0x7
00013cd5  f3a6               rep cmpsb byte [si], [di]  {cp30064}
00013cd7  7403               je      0x13cdc

00013cd9  ba0000             mov     dx, 0x0

00013cdc  5f                 pop     di
00013cdd  07                 pop     es {var_a}
00013cde  5e                 pop     si
00013cdf  1f                 pop     ds {var_6}
00013ce0  8bca               mov     cx, dx
00013ce2  5a                 pop     dx
00013ce3  5b                 pop     bx
00013ce4  b444               mov     ah, 0x44  
00013ce6  8ac1               mov     al, cl
00013ce8  e8b3f8             call    sub_1359e  
00013ceb  33c0               xor     ax, ax  
00013ced  c3                 retn     {__return_addr}
 

Dagwood

Experienced Member
Joined
Oct 16, 2018
Messages
55
Yep, same deal. I would be interested to find a newer version of the BIOS. When I examined CONF1520.EXE one thing that it does is get the BIOS date and sets a flag if it's older than 10/24/89 (Mine is 3/11/89). It then uses that flag to make choices during execution such as to skip some features that aren't supported on BIOS's older than 10/24/1989. I haven't examined the list deeply but some might just font related but I think some might relate to how it handles ROM's (which is something I've been toying with).
 

Dagwood

Experienced Member
Joined
Oct 16, 2018
Messages
55
I yanked the two EPROM's and dumped them with my programmer but I have found software dumps usually work just fine too on 286 and 386 machines so you might use Navratil to dump the BIOS the easy way. Plus then it comes out as one nice 'ready to eat' file instead of two binaries that need to be interleaved.
 

thanman

New Member
Joined
Apr 9, 2020
Messages
1
Wow! I've googled for a solution for a while now, and then I stumbled over this thread by chance! :D
I am trying to install a CF-card in my 1550sx, and I have gotten as far as ordering a programmer and some extra EPROMs.
My original plan, since I am a bit over my head with this, was to change one of the CPxxxx strings to the ID of my CF-card, but skipping the check in it's entirety seems like the better option.

@Klyball: Do you have the modified binary files for flashing the 1550sx?

And on a different subject; do any of you have any information on the expansion port in the battery bay? Is it a complete 16-bit ISA bus?
 

Klyball

Experienced Member
Joined
Feb 15, 2014
Messages
94
Location
Surrey, BC
Changing the id string , is not enough , you need to change a bunch of things in the routine as it looks for the "-" and the " " in the string so those need to be adjusted to something in the cf string plus the length in cx of the word to check. Jumping is easiest but you still need to pick where you put the chs and point to it with dx and then the check sum need to be repaired on each rom after it is split back up.
 

Dagwood

Experienced Member
Joined
Oct 16, 2018
Messages
55
Hey Kylball, taking a closer look at your photos I've not seen that particular ATA backplane. Would it be possible to see a picture of the front and back of it?
 

AmigaJules

Experienced Member
Joined
Dec 4, 2008
Messages
59
Location
Denton, TX
You got a 1530 to boot from a CF card?!? That's my holy grail!

I have one with an intermittent Conner failure (more down than up...) that occasionally still boots. I'd love to do what you did.

Any chance you can share your patched BIOS? I have a 512MB CF card, so am I right in assuming it would use the same C/H/S values yours did?
 

Klyball

Experienced Member
Joined
Feb 15, 2014
Messages
94
Location
Surrey, BC
Hi I did not do a 1530 yet only 1520 and 1550 , the 1530 i did had a different interface then normal , it had jumpers to select the drive.a regular 1530 will have the same protection code , all the info is above, i found the CHS of the CF cards can very , hook it up to the grid and run IDESDI from floppy or any other pc that has auto detect to get the CHS.

You got a 1530 to boot from a CF card?!? That's my holy grail!

I have one with an intermittent Conner failure (more down than up...) that occasionally still boots. I'd love to do what you did.

Any chance you can share your patched BIOS? I have a 512MB CF card, so am I right in assuming it would use the same C/H/S values yours did?
 

Klyball

Experienced Member
Joined
Feb 15, 2014
Messages
94
Location
Surrey, BC
Hey Kylball, taking a closer look at your photos I've not seen that particular ATA backplane. Would it be possible to see a picture of the front and back of it?

It is back in storage but i will when i dig it out. That 1530 has the conner routines stripped and you select the drive from a jumper on the backplane so all that is needed is the right CHS and any drive can work. all my other 1520,1530,1550 have the conner routines
 

AmigaJules

Experienced Member
Joined
Dec 4, 2008
Messages
59
Location
Denton, TX
Ah, I saw the photos and got over excited... I went back and re-read your post, now I get it.

Thanks for the tip on getting the CHS. I've got a cf > ide adapter on the way, as well as a couple of AM27C128 eproms for testing.

I pulled the BIOS on my 1530, dumped it and diff'd it with the odd & even files in the "1530 rom patch for any drive" archive that I pulled from RuGRiD before it went away.

The files are identical - it looks like that rom patch program prompts for drive ID string & CHS and writes out a modified BIOS - I'm afraid that doing that by hand is above my skill set, but hoping the program will handle it for me.

I hope I can pick your brain if I get stuck during the process.

I found an interesting thread at Vogons where someone did something similar for a Toshiba laptop BIOS (which have the same Conner limitations as some GRIDS) and added in XTIDE: https://www.vogons.org/viewtopic.php?f=46&t=57998
 

AmigaJules

Experienced Member
Joined
Dec 4, 2008
Messages
59
Location
Denton, TX
Some(?) progress:

I got the drive geometry & name/ID settings for a few CF cards (64MB, 512MB & 1GB) using another machine and the hddid.exe program.

I plugged the values for the 64MB card into the 1530ROM.BAS and wrote out the even & odd BIOS images. I burned them to new EPROMs.

I see the values for drive type 2 change to the correct values for my 64MB CF when I swap out the BIOS.

IMG_6647.jpeg
IMG_6648.jpeg

Unfortunately, even after setting drive type 2, after a reboot, setup shows no C drive.

IMG_6649.jpeg
IMG_6650.jpeg

Based on what I _think_ I understand of Klyball's post, the 1530ROM.BAS program I have may be for his type of 1530 (where you can just change the C/H/S).

Would any BIOS/Assembly Language gurus be willing to assist making Klyball's modifications to my BIOS image?

I'd love to retire the dying Conner drive in favor of a CF card.

Thank you!
 

AWPJudy

Member
Joined
Jul 27, 2020
Messages
10
i know in some ways it may seem like a slightly ridiculous approach, but as someone who stubbornly refuses to dive into x86 assembly..

what about manually changing a CF card geometry to match that of a conner, and then using a little cpld state machine or microcontroller to spoof the hardware ID any time it gets the identify drive command? it might be something people are interested in since some other machines of the era also had hard-coded drive lists.
 

Dagwood

Experienced Member
Joined
Oct 16, 2018
Messages
55
Patching the BIOS is old news. I did it, Klyball did it, and at least one other person that I know of, probably more. So the geo and ident issues have already been dealt with several times over. There are however other technical issues in which the bios won't reliably access modern devices. You will encounter the same issue if you use the hardware spoofing approach you mentioned. I have a functional but crude solution and am working on a quality solution which will be reliable under all circumstances.
 

SParent

Experienced Member
Joined
Mar 7, 2013
Messages
73
Location
Quebec City
Hello,
I have a CF to IDE adapter I want to connect to my 1520. I guess it's not just a matter of plugging it in. How did you do it? Is there some kind of short cable to build to adapt the pinout of the 1520 to the IDE standard?
Thanks!
 

AmigaJules

Experienced Member
Joined
Dec 4, 2008
Messages
59
Location
Denton, TX
Hello,
I have a CF to IDE adapter I want to connect to my 1520. I guess it's not just a matter of plugging it in. How did you do it? Is there some kind of short cable to build to adapt the pinout of the 1520 to the IDE standard?
Thanks!

I don't know what the 1520 looks like, but the 1530 has a "backplane" for the drives with female connectors where the IDE drive & floppy plug in for data & power.

I got some right angle IDE connectors and modified my CF adapter so it plugs in just like the 3.5" hard disk. Also added a small custom molex power cable to feed power to the CF adapter.
 

SParent

Experienced Member
Joined
Mar 7, 2013
Messages
73
Location
Quebec City
Yes, the 1520 has a similar backplane. By looking at the geometry of the connectors (two female 40 pins, one on the backplane and one on the CF/IDE card) I think a simple male to male connector would result in an inversion of the top and bottom rows of pins (ie pin 1 would be on pin 2, pin 2 on pin 1, and so on). So I figure I have to make a male/male cable that inverts top and bottom rows. Am I correct?
 

AmigaJules

Experienced Member
Joined
Dec 4, 2008
Messages
59
Location
Denton, TX
Yes, the 1520 has a similar backplane. By looking at the geometry of the connectors (two female 40 pins, one on the backplane and one on the CF/IDE card) I think a simple male to male connector would result in an inversion of the top and bottom rows of pins (ie pin 1 would be on pin 2, pin 2 on pin 1, and so on). So I figure I have to make a male/male cable that inverts top and bottom rows. Am I correct?

Here's a photo of my CF/IDE adapter & the right angle 40 pin connectors I bought.

IMG_6881.jpeg

I desoldered the male connector on the adapter and soldered the right angle connector to it. No cable needed. It plugs in upside down onto the drive backplane in my 1530.

Now I just need a BIOS that can work with it.
 
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